Calculating machine



De@ 9, 1941- T. M, BUTLER GALCULATING MACHINE Original Filed Aug. 31,v 1954 2 Shasta-Sheet l Pig. Z.

vlNvlsNToR mms SMM 9' ATTORNEYS Dec. 9, 1941.

. T. M. BUTLER CALGULATING MACHINE Original Filed Aug. 31, 1934- 2 Sheets-Sheet 2 AT'ORNE :MTM gwdg,

humaines, 194.1 2,265,626

UNITED STATES PATENTJGFFICE .ee-asses @Lemme Thomas M. Butler, Betr-alt, Mich., assigner te Burmnglu Adding Machine Gompany, Det-reis?, Mich., s. corpcrationcf Michigan AContinuatime ci application Serial Ne. 'eif August 31, 1934. This application @stehen l,

1957, Serial Nc. lflw l? mains. ft-M This invention relates c e and 12e-re rsnience, the index bars it and the racks l5,

particularly to the internal ccnsmzcten and tes-einer connecting parte, will be arrangement ci the interlocking cr" fiierenti l actuators. a calculating machine and is n eeninuetion ci A compact 'mrd emplcyed which may be my prior application Serial En. fled eecncniieall,particularly in mass August 3l, 1934= on. V csteinecl by providing the It is the purpose cr this investis-n prev-lne upper plete with e. nlnrslity ci benk of index an improved calculating machine ci small di numerals 2 9, eorremcnding to the banks ci mensions which lcan he msnnsetmezl eccs projecting tnrcsgn the key slots instead of nomicany, le placing these numerals directly en the key tops. It is a. further purpose .of this enfcn in si Thess Tse stamped ci otherwise plify the mechanisms by reducing line affixed finestre or indirectly an the plate l or size and complicity thereef.- nis-cn e member ererlying the plate. The index A better understanding ci numbers er standard size and areerrenged be had from the following aesc w clesely s sireity cf closely adjacent necticn with the drawings siii banks ser:espsndin\D te ne slots which een embodiment theres: and in is?" Ese es 'to brine; else :numerals Figure l is a right side sec f Y s calculating machine ce sti-.Wiance with this inventicu, i stentially actuel full she ef "f" Fig. 2 is a partiel plan 3 is en enlarged see. ci the keys end asscciste n ing' she key in ncrmel n depressed posiiicn in Fig. i a partiel perspecr kers ci one benk depressed csitlcn and tiefere been @per 3 e. detailed perse; Fis. l chewing the parte cccupy when the machlhe M witncut depressing s key; ss Fig. 6 is a detailed perspsci'ie pc i cf Pig. 5 the cenimn where another rnscperstlen neer lent ready cperaticn of all Referring te the drawings, tlie :Hamline prc- Ezeys. lne ccnstrsccn also permits of very eco:- vided with an upper keyboard plete l@ and a ncmc manufact" re ci the keys themselves be lower keyboard plate il 'wen and sin canse the kes' tops een formed very much port key stems l2., The tzvc plates are provided the manner ci heading nails.

n be explained. neet .ss/'aged et their tively needs ci smaller than prev-lele @cnil enctness ,ll vision ci i" ci suiieiezit size e key stems by the if n ni'. construction permits neyzoer size 'te dimensions inde reference numerals, eessir ci putting the reference e concave 'tcp surfaces, and 5 @linie-lent specs between key ttempted. for senz# with a plurality of banks nf slcts tlircugh which The keys ere weed tc normal position by a the key stems project to suppcrt tne stems fandV ecntinuens coil spring; 2l which extends longipermit vertical sliding movement thereof. P tudinally t euglicnt one benk ci keys passing Key stems l2 are adapted, when depressed, bo 4Q through suitable slots 22 formed in one edge of be positioned in the path cf stops i3 en index the key stems. The spring' is secured at each bars l! which are movable engt'dils Iem'- end to the edge cf the lower keyboard plate and wardly or to the right in Fis. l We h@ m21- between each key by ijf-shaped Wires 23 passing C11-meis Operated Until the SCGDS i3 m against n through slots in the lower keyboard plate Il a depressed key sbem. The rearward-end ci each and supporting the springs at points approxiindex bar is attached to a pivcteci actuator rack mately at the center of the key stems. The I5 which engages a pinion li carried by the springs thus tend to urge the. iles stems upwardly register pinions l1. The pininns il are risible and in a counterclcckwise direction, i. e., the .through a sight opening IS in e easing i5 ensprings tend is move the lower portion cf the closing the entire calculating machine. Per ecn- -55 stems to the right as viewed in Figs. 3, 4 and 5.

This sidewise movement of the key stems causes a notch 24 cut in the side or each stem to engage the lower plate i l when the key is depressed and hold the key in depressed position, thus retaining the lower portion of the key stem in position to engage lug i3 of the index bar lli when the machine is operated.

' To insure counterclockwise movement of the key stems upon depression rather than any other movement thereof due to directional pushing by the operator, the key stems are provided with elongated openings 25 through which a shaft 26 extends. In normal position, shaft 26 occupies the bottom of the slot as shown in Fig. 3. Upon depression of the key, the upper edge of the slot therein engages the shaftand due to the inclined edge of the slot enforces counterclockwise movement of the key stem at the final portion of its downward movement to insure engagement of notch 265 with the lower plate ll. The lower edge of notch 2G is also beveled off to assist in counterclockwise movement of the key lstem and to permit an easy release of the keys after each machine operation.

At the end of each machine operation all of the depressed keys are restored by means of bails 2l, there being a bail for each bank of keys. Each bail extends the full length of plate il and is pivoted at each end to plate ll by a shaft 2li supported by down-turned lugs 2Q of the plate l l. The bails 2l are urged clockwise about their pivots (Fig. 4) and against the lower right edges of the key stems by springs 3l. At the, end of each machine operation the bails are moved clockwise by means, later described, to release all ldepressed keys by moving the stems free of plate vin the event the machine is operated without depressing any keys. For this purpose bail 2l is provided with a downwardly extending arm 3d having a laterally projecting end or lug 35. In normal position of the machine arm 3d and lug 35 lie within a notch 3E formed in. the index bar le and prevent rearward movement of the index bar except for a slight movement permitted before lug 35 is engaged by the forward edge of notch 36. Upon depression of a key its stem is moved counterclockwise or to the right as viewed in Figs. 3, 4 and 5 under the influence of spring 2l and swings the bail 2l counterclockwise about its shaft 28, overcoming the action of spring 3|, thus moving arm 34 and lug 35 o'ut of notch 36 and out of the path of movement of index bar i4, permitting rearward movement of the latter 4to the limit determined by the depressed key.

Each bail 2l is also provided with a series of upwardly extending arms du, there being one arm for each key in the bank, to prevent depression of a second `key in any one column. For this purpose, the upper end of each arm 40 is bent over horizontally to provide a lug 4l for each key adapted to engage in slots 2 4 of the keys when undepressed and in upper notches 42 (Figs. 3 and 4) of the depressed keys each time any one key is depressed in a bank of keys. That is, prior to key depression the lugs 4l are clear of all notches, but engage therein according to whether the key is depressed or undepressed when the bail is swung about its p ivot. `Provision is also made to prevent "deprssilm zeroize the machine.

of a key after the machine has started a stroke of operation. For this purpose lug di of each bail 2'! is provided with a downwardly extending inclined nger 43. As can beseen from Fig. 5, if a key has not been depressed in. a particular key bank and the machine is given a stroke of operation, index bar lil is moved slightly rearwardly until the forward edge of notch 36 engages the lug 35 which action imparts'a longitudinal movement to bail El on its shaft 28, thus moving nger (i3 into the notches 2li of all undepressed keys preventing depression of any of the keys `while the machine is being operated. At the end of a machine operation each index bar lil is moved forward to its normal position by a shaft Q4. Shaft lli is supported by a swinging bail dilo and engages fingers (Fig. l) projecting from y each index bar ld.

The bail is also utilized to prevent misoperation of the machine such as an attempt to depress one or more of the keys with the left hand while operating the machine with the right hand, with the result that a key is partially depressed when the machine starts to operate. Assuming such an attempted misoperation, it is apparent that a 'partial depression oi a key would prevent entry of lug il in. slots 2li or i2 and also prevent rearward movement of the bail because of engagement of finger i3 with the side of the key. To prevent this type of misoperation, arm 3Q is provided with a forwardly projecting lip 37, which under the conditions mentioned prevents rocking of bail 2l. At the rst stage of such a misoperation, i. e., starting operation with a key partially depressed, bar i4 moves rearwardly slightly until the forward edge of notch 35 lies behind lip 3l as shown in Fig. 6 and prevents further rocking of the bail and thus prevents complete depression of said partially depressed key as well as release of bar ifi. This prevents damage to the machine and an erroneous entry in the machine.

An error key is provided in the form of a button i6 projecting through an elongated slot il formed in the upper plate l@ and secured to a slide lilmounted for horizontal sliding movements on the underside of plate ill.

Each bail 2l is provided near its rearward end with an upstanding arm i9 (Figs. 3 and 4) extending into a notch 5l) cut in slide 48. To release any and all depressed keys when an error is discovered it is only necessary to move slide 48 to the right by moving button 46 to the right which movement of slide da moves arm 49 to the right (Fig. 3) swinging bail 27 clockwise (Fig. 4) to release the depressed keysfrom the lower keyboard plate, permitting raising of the keys by springs 2i. It is understood, of course, that each bail 27 has a similar arm 49 engaging in a similar notch 50 so that all keys of all banks are released at each movement of slide 48.

Knob 46 and slide 48 are also used to clear or This is accomplishedby moving the knob and slide to the left. This movement also moves the arms 49 of each bail 2l to rock all bails in a counterclockwise direction. This moves the downwardly extending arms 34 and the lugs 35 out of the path of index bars I4 so that when the machine is given a stroke of operation the index bars i4 will be released to move rearward under control of the zeroizing mechanism of the register pinions (not shown).

As previously stated, bail 2l is moved clockwise at the end of each operation to release all' keys.

This is accomplished through slide 48 in the following manner.

In the normal position of slide 48, the finger knob or button 46 is yieldingly held in its center position, y(Fig. 2) by a stud 46l which extends downwardly from the slide and is engaged by a crank 55 pivoted at 56 to the upper keyboard plate I and which is urged clockwise by spring 51. A second lever 58 also pivoted at 56 and engaging stud 46*aL has an arm 59 extending rearward where it contacts a iixed stud 60 extending from the keyboard plate I0, this latter arm is urged in a counterclockwise direction by a spring 6l. Spring 6I is much stronger than spring 51 and serves to hold the arm 59 against the stud 60 and incidentally to. position knob 46 in the center of its slot. Knob 46 ,may b'e moved to the left for total taking to rock lever 55 or to the ,right to rock all bails 2l to restore depressed keys.

When the machine completes its'stroke 'of operation crank'55 is positively moved clockwise by lever 62 which results in releasing all depressed keys just as the machine arrives in normal position. Lever 62 is pivoted at 63, Fig. 1, to the left side of the machine' and contains a downwardly extending lug 64 which under certain conditions engages a forwardly extending arm 65 fixed to the left end of shaft 44 and extending rearward where it is pivoted at -56 to a crank G1 secured to the shaft 68. Each time the machine is given a stroke of operation shaft 68 is rotated a single revolution in a clockwise direction and lever 65 is reciprocated and given an voscillating movement so that at the extreme end of the machine operation `the forward end of lever 65 engages lug 64 and rocks lever 62 momentarily in a clockwise direction and then disengages it so as to allow the knob 46 (Fig. 2) to restore to its normal position.

It will be appreciated by those skilled in the art that the placing of the index numbers on v the keyboard plate which permits reduction in size of the key tops which in turn permits moving the keys closer together makes it possible to provide a much smaller keyboard without sacrificing visibility or thenecessary finger clearance between each key. For instance, the usual standard keyboard for the so-called portable calculating machines which have heretofore been considered small, requires a depth of approximately 6%", whereas the present arrangement reduces this dist-ance to approximately 4". Likewise the width of the keyboard can be reduced from the conventional keyboard size of approximately 3" for a 5-bank machine to approximately 21/2". It is understood, of course,

that these 'dimensions are purely illustrative and relative to illustrate the actual possible reduction in size. As heretofore stated, Fig. 1 represents substantially a full size machine which may be made in accordance with this invention. The foregoing construction of the associated mechanisms, particularly the use of a single bail to perform five functions, is much simpler than that usually employed in calculating machines, eliminates many parts, occupies considerably less space, and may be manufactured at much lower cost.

It will also be obvious to those skilled in the art that minor changes may be made in the details of construction without departing from the spirit and scope of this invention as defined in the appended claims. i

- I claim:

1. vA calculating machine keyboard comprising a frame, a key having astem slidably mounted in said frame to enable said key to be depressed from a normal to a depressed position and to be restored to normal, said key stem also being so formed and mounted that its lower end may be swung laterally when the key is depressed'to a predetermined position, spring means urging said key toward its normal position, cam means on said key stem acting against a fixed portion of said frame to positively move Vthe lower end of said key stem laterally when said key is depressed to a predetermined position, latching means engaged by said key stem, when said stem is moved laterally, to thereby releasably hold -said key in depressed position, and restoring means for returning the lower end of said key stem laterally toward normal to release it from said latohing means to enable said spring means to restore said key to normal.

2. A calculating machine keyboard comprising upper and lower keyboard plates, a key having a stem slidably mounted in said plates to enable -said key to be moved from a normal to a depressed position and to be restored to normal, said key stem also being so formed and mounted that its lower end may be swung laterally in. said lower keyboard plate when said key is depressed to apredetermined position, a cam slot in said key stem whose edge engages a stud on said frame to positively move the lower end of said key stem laterally when said key is depressed to a predetermined position, spring means urging said key toward normal position, said key stem having a notch therein engaging over the lower keyboard plate when the lower end of said key stem is moved laterally, and means for moving the lower end of said key stem laterally to free it of said lower plate to enable said spring means to restore said key to normal.

3. AY calculating machine keyboard comprising a frame, a bank of keys having stems slidably mounted in said frame to enable` said keys to be selectively moved from a normal to a depressed position and restored lto normal, each key stem also being so formed and mounted that its lower end can be moved laterally when the key is depressed to a predetermined position, a spring engaging `the side edges of and operably connected to said stems, said spring being anchored at its ends and between each two key stems in such a manner that, when one of said keys is depressed, said spring tends to restore it to normal and also tends to move the lower end of said key stem laterally, latching means engaged by each key stem, when its lower end is moved laterally by said spring after the key has been depressed, to thereby releasably hold said key in depressed position, and means for moving the lower end of said key stem to free it of said latching means to enable said spring to restore said key to normal.

4. A calculating machine keyboard comprising upper and lower keyboard plates, a bank of keys having stems slidably mounted in said plates to enable said keys to be selectively moved from a normal to a depressed position and restored to v normal, each key stemalso being so formed and mounted that its lower end can be moved laterally in said lower plate when the key is depressed to a predetermined position, a coil spring positioned in notches in the side edges of said key stems, said spring beinganchored at its ends and between each two key stems in such a manner that, when one of said keys is depressed, said I spring tends to restore it to normal and also tends to move the lower end of said key stem laterally, each key stem having a notch therein which engages over the lower plate, when the lower end of the key stem is moved laterally by said spring after its key has been depressed, to thereby releasably hold said key in depressed position, and means for moving the lower end of said key stem to free it ofV said lower plate to enable said spring to restore said key to normal.

5. In a calculating machine having differential actuators; the combination of a keyboard comprising a frame, a bank of keys having stems slidably mounted in said frame to enable said keys to be selectively moved from a normal to a depressed position and returned to normal, each key stem also being so formed and mounted that its lower end may be swung laterally when its key is depressed to a predetermined position, a bail positioned along said bank of keys and swingably mounted on said frame, said bail being normally positioned to act as a zero stop for the dierential actuator for said bank of keys, means acting, when a key is depressed to said predetermined position, to swing the lower end or the key stem laterally to move it into the path of its diiierential actuator and cause it to-swing said bail out ci the path of said actuator,'latching means engaged by said key stem when it is moved laterally to thereby releasably hold said key in depressed position, and means for moving said bail to return it to zero-stopping position and return said key stem laterally.

6. In a calculating machine having diierential actuators; the combination of a keyboard comprising a frame, a bank of keys having stems slidably mounted in said frame to enable said keys to be selectively moved from a normal to a depressed position and returned to normal, each key stem also being so formed and mounted that its lower end may be swung laterally whenv its key is depressed to a predetermined position, spring means urging said keys toward normal position and also urging the lower ends of said key stems laterally, a bail positioned along said bank of keys and pivoted on said frame, said bail being normally positioned to act as a zero stop for the diierential actuator for said bank of keys, each key stem having portions engaging said bail and acting, when a key is depressed to said predetermined position, to swing the bail out of the path of said actuator as the lower end of the key stem is swung into the path of said actuator, latching means engaged by said key stem when it. is moved laterally to thereby releasably hold said key in depressed position, and means for swinging said bail laterally to normal zero-stopping position, said bail engaging the key stem of the depressed key to swing it laterally to release it from said latching means.

7. In a calculating machine having differential actuators; the combination of a keyboard comprising a frame, a bank of keys having stems slidably mounted in said frame to enable said keys to be selectively moved to a depressed position and returned to normal, each key stem also so formed and mounted that its lower end may be moved laterally when its key is depressed to a predetermined position, a bail positioned along said bank of keys and pivoted on said keyboard frame, said bail normally being in a position in which it acts as a zero stop for the diierential actuator for said bank of keys, means acting, when a key is depressed to said predetermined position, to move the lower end of the key stem aaeaeac laterally to place it in the path of said actuator and cause it to move said bail to disable the latter as a zero stop, said bail, when it is so moved, having portions entering notches in the key stems of undepressed keys of said bank to prevent their depression while the first key remains depressed. 8. vIn a calculating machine having dierential actuators and adapted to be given cycles of operation; the combination of a keyboard comprising a frame, a bank of keys having stems slidably mounted in said frame to enable said keys to be selectively moved to depressed -position and returned to normal, each key stem also being so formed and mounted that its lower end may be swung laterally when the key is depressed to a predetermined position, a bail positioned along said bank of keys, said bail being pivotally and slidably mounted on said frame and normally being in a position in the path of said actuator so that it acts as a zero stop for the diierential actuator for said bank, means operating, when a key is depressed to said predetermined position,v to move the lower end of the key stem laterally into the path of said dierential actuator and cause said key stem to engage said bail and swiner it on its pivot to thereby move said bail out of the path of said actuator, said bail having por= tions which, when said bail is so swung, engage with the undepressed keys of said bank to hold them against depression, means including said actuator and operating at the beginning of a machine cycle to slide said bail, said bail also having portions which, by said sliding of the bail, are moved to a position to lock all of the keys oi said bank against movement during a portion of the machine cycle, and means operating later in the machine cycle to restore said bail to normal and to release said keys.

9. In a calculating machine adapted to be given cycles of operation and having differential actuators; the combination of a keyboard comprising a frame, a bank of keys having stems slidably mounted on said frame to enable said keys to be selectively movable from a normal to a depressed position and to be returned to normal, a zero stop for the differential actuator for said bank of keys, each of said key stems having portions acting, when its key is fully depressed, to move said zero stop free of said actuator, and means including said actuator acting at the beginning of a machine cycle to directly block said V tially depressed at the time a machine cycle starts.

10. In a calculating machine adaptedv to be given cycles of operation and having diierential actuators; the combination of a keyboard comprising a frame, a bank of keys having stems slidably mounted on said frame to enable said keys to be selectively movable from a normal to a depressed position and'to be returned to normal, a zero stop for the diierential actuator for said bank of keys, each of said key stems having portions engaging said zero stop tofmove said zero stop free of said actuator when its key is fully depressed, and means acting at the beginning of a machine cycle to move said actuator to directly block said zero stop against movement to actuator-releasing position when a key in said bank is only partially depressed at thetime a machine cycle starts, said zero stop, when blocked, prereason of the engagement between said zero stop and said key stems. v

11. In' a calculating machine adapted to be given cycles of operation and having diierential actuators; the combination of a keyboard comprising a frame, a bank of keys having. stems slidably mounted on said frame to enable said keys to be selectively movable from a normal to a depressed position and to be returned to normal, and a zero stop for the differential actuator for said bank of keys permitting a slight movement of said diiferential actuator at the beginning of a machine cycle when said zero stop is in actuator-arresting position, each of said key stems having an operative connection with said zero stop acting, when its key is fully depressed, to move said zero stop free of said actuator', said actuator having portions acting, when said actuator is moved slightly at the beginning of a machine cycle while said zero stop is in actuatorarresting position, to directly block said zero stop against movement to actuator-releasing position, said zero stop then acting through the operative connections with the key stems to prevent full depression of any key.

12. In a calculating machine adapted to be given cycles of operation and having differential actuators; the combination of a keyboard comprising a frame, a bank of keys having stems mounted on said frame to enable said keys to be selectively movable from a normal to a depressed position and to be returned to normal, and a pivoted bail along said bank of keys acting as a zero stop for the diiierential actuator for said bank of keys, said zero stop, when in actuc -zero-stop bail to block movement of said bail to actuator-releasing position and to prevent full depression of any of said keys.

13. In a calculating machine adapted to be given cycles of operation; of a keyboard comprising a frame, a bank of keys having stems slidably mounted in said frame to enable said keys to be selectively moved from a normal to a depressed position and returned to normal, a key latching bail engageable by the stem of each key upon full depression thereof to move said bail to a position to latch the other keys of said bank against' depression, and means normally operating at the beginning of a machine cycle when no key in said bank is depressed, to move said bail to position it to lock all of said keys, said means operating at the beginning of a machine cycle started with any of the keys in said bank partially depressed, to prevent movement of said latching bail by said keys, whereby said latching bail then prevents full depression of any of the keys in said bank.

14. In a calculating machine having differential actuators and adapted to be given cycles of operation; the combination of a keyboard comprising a frame, a bank of keys having stems slidably mounted in said frame to enable said keys to be selectively moved from a normal to a depressed position and returned to normal, and a key latching bail engageable by the stem of each key upon full depression thereof to move said bail to a position to latch the other keys of said bank against depression, the actuator for said bank of keys moving at the beginning of a machine cycle when no key in said bank is depressed to move said bail to position it to lock all of said keys, said actuator, by its movement at the beginning of a machine cycle started with any of the keys in said bank partially depressed, acting to prevent movement of said latching bail by said keys, whereby latching bail then prevents full depression of any of the keys in said bank. l 15. In a calculating machine having differential actuators and adapted to be given cycles of operation; the combination of a keyboard comprising a frame, a bank of keys having stems slidably mounted in said frame to enable said keys to be moved from a normal to a depressed position and returned to normal, a bail movably mounted on said frame along said bank of keys,

said bail normally being positioned to act as a zero stop for the actuator of said bank but being movable by said keys, when one of them is fully depressed, to free said actuator, portions of said bail, when-it is thus moved, engaging the stems of undepressed keys to prevent their depression, said actuator moving at the beginning of a machine cycle when no key in said bank is depressed to move said bail to position portions of it to block operation of al1 of said keys during a predetermined portion of the machine cycle, and means operating during said machine cycle to restore said bail to normal, said actuator, by its movement at the beginning of a machine cycle started with any of the keys of said bank partially depressed, acting to block movement of said bail to thereby prevent its movement to actuator-releasing position and also cause it to prevent full depression of any of said keys.

16. In a calculating machine having dinerential-actuators and adapted to be given cycles of operation; the combination of a keyboard comprising a frame, a bank of keys having stems slidably mounted in said frame to enable said keys to Abe moved from a normal to a depressed position and returned to normal, said key stems also being so formed and mounted that their lower ends are movable laterally, a bail positioned along said bank of keys, said bail being pivotally and slidably mounted on said frame and losingA urged to a position inengagement with the lower ends of said key stems in which position a portion oi said bail acts as a zero stop for the actuator ci said bank, means acting, when a key is fully depressed, to move the lower end of the stein of said key laterally, latching means engaged by said key stem when so moved to releasably hold the key depressed, said key stem, when moved laterally, engaging said bail and moving it on its pivot out of the path of engagement of said actuator, said bail, when so moved, having portions moving into engagement with the stems of undepressed keys to latch them against depression, said actuator moving at the beginning of a machine cycle when no key in said bank is depressed to slide said bail to cause portions of it to enter` notches in all of said keys to thereby lock all of the keys against movement during a predetermined part of the machine cycle, and means operating to restore said bail to normal, said bail during its restoring movement engaging the lower end of the depressed key to move it laterally out of latching engagement with the latching means, said actuator by its movement at the 'beginning of a machine cycle started with any or the keys of said bank partially depressed, acting to block movement oi said bail to thereby prevent its movement to actuator-releasing position and also cause it to prevent full depression of any of said keys.

i?. In a. calculating machine having dierentiai actuators and adapted to 'ne given cycles of operation; the combination of a, keyboard comprising a frame, a bank of keys having stems siidahly mound in said frame to enable said keys to he moved from a normal to a depressed position. and returned to normal, said key stems l5 also being so formed and mounted that their tower ends are movabie laterally, a bail positienes?. along said bank of keys, said `nail being pivotaiiy and slidably mounted on said frame and being urged to a position in engagement with the iov-Jer ends of said key stems, in which position a portion of said hail acts as a aero stop for the actuator of said bank permitting said actui ator a siight movement at the beginning oi a machine oyeie when said hail is in .zero-stopping position, means acting, when a key is fully de pressed, to move the lower end of the stem of aaeaeae said key laterally, latching means engaged by said key stem whenso moved to releasably hold the key depressed, said key stem, when moved laterally, engaging said bail and moving lt on its pivot out of the path of engagement of said actuator, said bail, when so moved, having portions moving into engagement with the stems of undepressed keys to latch them against depression, means normally operating automatically at the beginning of a machine cycle to move said actuator to slide said bail to cause portions of it to enter notches in all of said keys to thereby lock all oi' the keys against movement during a predetermined portion of the machine cycle, means operating to restore said bail vto normal, said bail during its restoring movement engaging the lower end oi the depressed key to move it laterally out oi latching engagement with the latching means, and means rendered operative by said slight movement of said actuator at the beginning of a machine cycle started prior to full depression of any of the keys of said blank for blocking movement of said bail to thereby prevent its movement to actuator-releasing posi= tion and also cause it to prevent full depression of any of said keys.

THOMAS M. 

